Dual-task interference during obstacle clearance in healthy and balance-impaired older adults

Background and aims: To investigate dual-task interference between a concurrent cognitive task (auditory Stroop test) and obstacle avoidance in older adults with or without a history of falls. Methods: Gait performance (temporal-distance parameters, range of motion and peak velocity of the center of mass) and verbal reaction time (VRT) in the secondary auditory Stroop task were monitored in 12 healthy young adults, 12 healthy older adults and 12 balance impaired older adults (BIOA) while they sat or walked with and without an obstacle in their path. VRT was used as an indicator of attention given to the secondary Stroop task. Results: Under dual-task situations, all older participants reduced their gait velocity, taking longer strides and wider steps. BIOA significantly increased toe clearance of their trailing limb during obstacle avoidance. In all participants, cognitive attention to the Stroop task, as measured by VRT, was diminished as the level of difficulty in the activity increased; however, the effect was blunted in BIOA compared to healthy subjects. Conclusions: Performing two tasks was highly inefficient among BIOA, as their performance in the gait and secondary task were both modified under dual-task situations. It is possible that dual-task interference in BIOA may be due to the inability to shift attention between the two tasks without primarily prioritizing gait. The findings suggest that BIOA should perform one task at a time in daily activities in order to reduce the risk of falling.